The answer to this question like answers to every question in Pensionland starts with, tell me more first.
Here is how a financial columnist recently responded to this question. Paraphrasing the Q & A:
Asked the reader: I’m going to remarry and how can I have my children inherit the money in my 401(k) account and not my soon to be new spouse?
Answered the columnist: It’s very simple, Just go to whoever is managing your 401(k) money and complete a new beneficiary form.
Maybe the columnist is right. Maybe it is that simple. But one thing I’ve learned over the years is that nothing is simple in Pensionland. Some retirement plans require by law that the spouse is the automatic beneficiary unless he or she consents otherwise in writing. Let jump ahead and assume that this is the case here but that there was no spousal consent obtained. You can take it from here.
This is why disclaimers are good things.